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received email from the contractor who gave me the "reasonable" quote on the 3-ton Carrier Performance 2-stage last week. He provided an unsolicited proposal on the 3-ton Greenspeed, along with the AHRI certificate.

Forgot to mention his email also suggested installing a simple zoning system (3-4 zones), which would add close to 40% to the cost of the Infinity install. My opinion (and that of other bidding contractors) is that small tweaks to my existing ductwork (i.e., a damper or two coming off the plenum) will be enough to balance airflow and reduce the 6-8* temp difference from front to back that I have when supply vents in the front bedrooms (closest to the plenum) are fully open.

Question: If I install the Infinity HP, does it NEED to have zoning to work properly? IMHO, zoning is overkill for my relatively small 1827sf one-story home.

Depends on your comfort level. IMHO they should be able to get within 3-4 degrees on a single story home w/o using zoning. The rooms with large glass areas will tend to be warmer when the sun is on that side of the house (duh ), zoning would help with that. I've seen WAY too many homes with bad ductwork, the rooms being close to the air handler are over heated/cooled, the rooms furthest away don't get enough air. The fix requires redoing ductwork, not adding a zone system.

I agree. Just wanted to make sure there's not some "techy-tech" complication with the GreenSpeed where it wouldn't operate properly without "zoning" if there's still a 3-4* difference from front to back once the ductwork is fixed.

Nope, if the duct work is bad/poorly designed no fancy equipment will overcome that. I'm a BIG fan of using mid level equipment that's correctly sized (or even a little "undersized" since manual J typically oversizes). Use the difference in price to fix ductwork/home envelope. Overall energy bills will end up being lower and you will have better comfort.

Once you get into the 2 stage equipment (which accounts for less than 10% of what's installed in our area) parts tend to become expensive special order items and only the best techs are good enough to work on them. Getting people to move up from the builder grade stuff is hard enough, high end equipment is a tough sell. Not sure how much 2 stage stuff is typically installed in your area.

Once you get into the 2 stage equipment (which accounts for less than 10% of what's installed in our area) parts tend to become expensive special order items and only the best techs are good enough to work on them. Getting people to move up from the builder grade stuff is hard enough, high end equipment is a tough sell. Not sure how much 2 stage stuff is typically installed in your area.

I've had different contractors tell me different things... probably based mostly on what they'd like to sell me! Some (especially the Trane dealers) said one or more of their 2-stage offerings is "most popular", by far. Others said they rarely sell the 2-stage equipment these days since the IRS tax credits expired. I tend to believe the latter. I have a variety of quotes on 2-stage and the less expensive 15 SEER units and I've searched through the county's online permit site to get a feel for who's installed which units in my neighborhood over the past year. While the site doesn't reveal model numbers, it does show the cost estimate for the job. Looks to me like the higher cost 2-stage installs have been few and far between over the past year, regardless of what the dealers would like me to believe!

Checking dealer permits also gives me an idea of which of the one-man shops are in this business for beer money only!

You didnt have zoning before, and based upon all youve written, not sure where the benefit would be. I suspect it was offered as "you could do" rather than "you need to do."

I agree on lack of benefit. On re-reading the email offering to sell me the Greenspeed in combination with zoning, it sounds like he's looking to install them together so I won't "notice" temperature differences, like I do now. It appears his objective, besides profit motive, may be not having to address the duct "tweaking" i'd like him to do during the install. Is it really that much work to put in a couple of hand dampers?

Contractors don't like messing with ductwork. It's labor intensive and has one of the lowest profit margins. Repairing bad ductwork will make a bigger difference in comfort than just about any other home improvement you can do.